Rework label mapping algorithms to be more in line with the RFC.

This patch presents a thoroughly review of the label mapping
algorithms. Most of the changes are minor bug fixes in the handling of
received label messages.

Additional improvements:
* Add a few more references to the Appendix A of the RFC5036 ("LDP
  Label Distribution Procedures") into the code;
* Add full multipath support;
* Send label withdraws when appropriate;
* Add label withdraw/release wildcard support.

NOTE: As a result of implementing only the "Liberal Label Retention" and
"Downstream Unsolicited" modes, we will never send a label request
("Request  Never"). And that means that we can ignore the following
notification messages: "Label Request Aborted", "No Label Resources",
"No Route" and "Label Resources Available". The following algorithms
mentioned in the RFC can also be ignored: "Timeout of Deferred Label
Request", "Detect Local Label Resources Have Become Available" and
"Receive Label Abort Request".

Now, considering that we only support one combination of all modes of
operation, we can say that we have an almost complete implementation of
the protocol.

ok claudio@

1 files changed, 44 insertions, 16 deletions

diff --git a/usr.sbin/ldpd/labelmapping.c b/usr.sbin/ldpd/labelmapping.c
index 1322e481197..df62ce14e44 100644
--- a/usr.sbin/ldpd/labelmapping.c
+++ b/usr.sbin/ldpd/labelmapping.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: labelmapping.c,v 1.31 2015/02/09 11:53:25 claudio Exp $ */
+/*	$OpenBSD: labelmapping.c,v 1.32 2015/07/19 20:54:16 renato Exp $ */
 
 /*
  * Copyright (c) 2009 Michele Marchetto <michele@openbsd.org>
@@ -41,6 +41,7 @@
 void		gen_label_tlv(struct ibuf *, u_int32_t);
 void		gen_reqid_tlv(struct ibuf *, u_int32_t);
 void		gen_fec_tlv(struct ibuf *, struct in_addr, u_int8_t);
+void		gen_wcard_fec_tlv(struct ibuf *);
 
 int	tlv_decode_label(struct nbr *, struct ldp_msg *, char *, u_int16_t,
     u_int32_t *);
@@ -80,10 +81,13 @@ send_labelmessage(struct nbr *nbr, u_int16_t type, struct mapping_head *mh)
 		}
 
 		/* calculate size */
-		tlv_size = LDP_MSG_LEN + TLV_HDR_LEN + FEC_ELM_MIN_LEN +
-		    PREFIX_SIZE(me->map.prefixlen);
-		if (type == MSG_TYPE_LABELMAPPING ||
-		    me->map.flags & F_MAP_OPTLABEL)
+		tlv_size = LDP_MSG_LEN + TLV_HDR_LEN;
+		if (me->map.flags & F_MAP_WILDCARD)
+			tlv_size += FEC_ELM_WCARD_LEN;
+		else
+			tlv_size += FEC_ELM_PREFIX_MIN_LEN +
+			    PREFIX_SIZE(me->map.prefixlen);
+		if (me->map.label != NO_LABEL)
 			tlv_size += LABEL_TLV_LEN;
 		if (me->map.flags & F_MAP_REQ_ID)
 			tlv_size += REQID_TLV_LEN;
@@ -99,9 +103,11 @@ send_labelmessage(struct nbr *nbr, u_int16_t type, struct mapping_head *mh)
 
 		/* append message and tlvs */
 		gen_msg_tlv(buf, type, tlv_size);
-		gen_fec_tlv(buf, me->map.prefix, me->map.prefixlen);
-		if (type == MSG_TYPE_LABELMAPPING ||
-		    me->map.flags & F_MAP_OPTLABEL)
+		if (me->map.flags & F_MAP_WILDCARD)
+			gen_wcard_fec_tlv(buf);
+		else
+			gen_fec_tlv(buf, me->map.prefix, me->map.prefixlen);
+		if (me->map.label != NO_LABEL)
 			gen_label_tlv(buf, me->map.label);
 		if (me->map.flags & F_MAP_REQ_ID)
 			gen_reqid_tlv(buf, me->map.requestid);
@@ -121,7 +127,7 @@ recv_labelmessage(struct nbr *nbr, char *buf, u_int16_t len, u_int16_t type)
 {
 	struct ldp_msg		 	 lm;
 	struct tlv			 ft;
-	u_int32_t			 label, reqid = 0;
+	u_int32_t			 label = NO_LABEL, reqid = 0;
 	u_int8_t			 flags = 0;
 
 	int				 feclen, lbllen, tlen;
@@ -228,7 +234,7 @@ recv_labelmessage(struct nbr *nbr, char *buf, u_int16_t len, u_int16_t type)
 		case TLV_TYPE_LABELREQUEST:
 			switch (type) {
 			case MSG_TYPE_LABELMAPPING:
-			case MSG_TYPE_LABELABORTREQ:
+			case MSG_TYPE_LABELREQUEST:
 				if (ntohs(tlv.length) != 4) {
 					session_shutdown(nbr, S_BAD_TLV_LEN,
 					    lm.msgid, lm.type);
@@ -260,7 +266,6 @@ recv_labelmessage(struct nbr *nbr, char *buf, u_int16_t len, u_int16_t type)
 
 				memcpy(&labelbuf, buf, sizeof(labelbuf));
 				label = ntohl(labelbuf);
-				flags |= F_MAP_OPTLABEL;
 				break;
 			default:
 				/* ignore */
@@ -299,26 +304,35 @@ recv_labelmessage(struct nbr *nbr, char *buf, u_int16_t len, u_int16_t type)
 		int imsg_type = IMSG_NONE;
 
 		me->map.flags |= flags;
-		if (type == MSG_TYPE_LABELMAPPING ||
-		    me->map.flags & F_MAP_OPTLABEL)
-			me->map.label = label;
+		me->map.label = label;
 		if (me->map.flags & F_MAP_REQ_ID)
 			me->map.requestid = reqid;
 
 		switch (type) {
 		case MSG_TYPE_LABELMAPPING:
+			log_debug("label mapping from nbr %s, FEC %s, "
+			    "label %u", inet_ntoa(nbr->id),
+			    log_fec(&me->map), me->map.label);
 			imsg_type = IMSG_LABEL_MAPPING;
 			break;
 		case MSG_TYPE_LABELREQUEST:
+			log_debug("label request from nbr %s, FEC %s",
+			    inet_ntoa(nbr->id), log_fec(&me->map));
 			imsg_type = IMSG_LABEL_REQUEST;
 			break;
 		case MSG_TYPE_LABELWITHDRAW:
+			log_debug("label withdraw from nbr %s, FEC %s",
+			    inet_ntoa(nbr->id), log_fec(&me->map));
 			imsg_type = IMSG_LABEL_WITHDRAW;
 			break;
 		case MSG_TYPE_LABELRELEASE:
+			log_debug("label release from nbr %s, FEC %s",
+			    inet_ntoa(nbr->id), log_fec(&me->map));
 			imsg_type = IMSG_LABEL_RELEASE;
 			break;
 		case MSG_TYPE_LABELABORTREQ:
+			log_debug("label abort from nbr %s, FEC %s",
+			    inet_ntoa(nbr->id), log_fec(&me->map));
 			imsg_type = IMSG_LABEL_ABORT;
 			break;
 		default:
@@ -436,6 +450,20 @@ gen_fec_tlv(struct ibuf *buf, struct in_addr prefix, u_int8_t prefixlen)
 		ibuf_add(buf, &prefix, len);
 }
 
+void
+gen_wcard_fec_tlv(struct ibuf *buf)
+{
+	struct tlv	ft;
+	u_int8_t	type;
+
+	ft.type = htons(TLV_TYPE_FEC);
+	ft.length = htons(sizeof(type));
+	ibuf_add(buf, &ft, sizeof(ft));
+
+	type = FEC_WILDCARD;
+	ibuf_add(buf, &type, sizeof(type));
+}
+
 int
 tlv_decode_fec_elm(struct nbr *nbr, struct ldp_msg *lm, char *buf,
     u_int16_t len, u_int8_t *type, u_int32_t *prefix, u_int8_t *prefixlen)
@@ -446,7 +474,7 @@ tlv_decode_fec_elm(struct nbr *nbr, struct ldp_msg *lm, char *buf,
 	off += sizeof(u_int8_t);
 
 	if (*type == FEC_WILDCARD) {
-		if (len == 0)
+		if (len == FEC_ELM_WCARD_LEN)
 			return (off);
 		else {
 			session_shutdown(nbr, S_BAD_TLV_VAL, lm->msgid,
@@ -460,7 +488,7 @@ tlv_decode_fec_elm(struct nbr *nbr, struct ldp_msg *lm, char *buf,
 		return (-1);
 	}
 
-	if (len < FEC_ELM_MIN_LEN) {
+	if (len < FEC_ELM_PREFIX_MIN_LEN) {
 		session_shutdown(nbr, S_BAD_TLV_LEN, lm->msgid, lm->type);
 		return (-1);
 	}